8-bit Microcontrollers中的主题 Re: 802.15.04 MC13192 Switch Channels

802.15.04 MC13192 Switch Channels

galahad — Tue, 12 Feb 2008 00:45:24 GMT

Hello,

how long does it take for a MC13192 design to hop to a different channel? I measured something about 9ms (XBee) and just can't believe that. Found nothing in the manuals. (PLL setup time?)

Thanks,

Joerg

Re: 802.15.04 MC13192 Switch Channels

RickN — Wed, 13 Feb 2008 22:07:11 GMT

Hi Joerg,

Some helpful information from the 13192RM (Section 3.10):

Time for Clear Channel Assessment (CCA): 278uS

Time for Energy Detect (ED): 342uS

Max payload Transmit Time from Idle: 4000uS

SPI register read/write time needed to change the frequency: 40uS (?)

OK, let's assume the 13192 is in the Idle Mode (Table 6.1): If you send a command to change the channel, and then transmit a full payload, you would be in the range of 5ms. If you are coming out of a low power mode, the times will increase also.

What/how are you measuring the 9ms?

The warmup time for TX or RX are independent of the channel ( frequency ) you have selected.

Thanks,

Rick

Re: 802.15.04 MC13192 Switch Channels

galahad — Thu, 14 Feb 2008 01:08:29 GMT

Rick,

thank you very much. We send a channel switch command and a small payload to an XBee module in API-Mode2. We look at the current consumption of the module also.

When XBee is in receive mode, after the channel switch command the current sinks significantly for about 9ms, then rise to receive level again and shortly after that to transmit level.

It looks like the module needs about 9ms to switch between receiving/new channel/receiving.

Another test: It takes almost the same time from last byte of channel command to first byte of the acknowledge. (XBee API)

9 ms is too long for a software process in the MPU. I guess it has something to do with the 2.4 GHz PLL. Can you confirm that?

Re: 802.15.04 MC13192 Switch Channels

galahad — Fri, 22 Feb 2008 15:27:13 GMT

Rick,

don't you want to confirm the 9..10ms channel switch time?

Re: 802.15.04 MC13192 Switch Channels

RickN — Sat, 23 Feb 2008 04:03:35 GMT

Hi,

You need to have a better idea of what modes the software using. Are they putting the device to sleep? Looking at the power consumption is good, but you need to take a look at what the software is doing. The numbers I presented are for going from idle to transmit, and they are fine. You may be going into a sleep mode.

- Rick

Re: 802.15.04 MC13192 Switch Channels

galahad — Mon, 25 Feb 2008 23:16:30 GMT

Rick,

i'm definitely not in sleep or any other power-down mode. The modul is sending all the time every 20..30ms for test reasons. (Verified using a network sniffer). After the channel switch command, power drops for 9..10ms, after that delay everything goes on.

- Joerg